THIS IS A RUSH TRANSCRIPT. THIS COPY MAY NOT BE IN ITS FINAL FORM AND MAY BE UPDATED.

[16:30:05] JAKE TAPPER, CNN HOST: Dan, thanks so much for being here. Welcome to CNN.

So, let me start. Martin O'Malley and Bernie Sanders, realistically speaking, does either of them have a shot?

DAN PFEIFFER, CNN POLITICAL COMMENTATOR: I think they have a shot, in the sense that they're running.

But if either one of them were to win, it would be the greatest upset in the history of politics.

TAPPER: You -- let's talk about Hillary Clinton, who is obviously way favored on the Democratic side of the aisle.

You said that the political world had lost its mind about the Hillary Clinton e-mails. You don't think that this is something the American people should care about? She wiped her server cleaned. She used a private server for official business?

PFEIFFER: No, I don't mean that it's not something that should be looked at. And I think it is.

What -- my point was, when this all happened, every, you know, political prognosticator and pundit was saying this was going to be an existential threat to her campaign, some said. And we have a poll out in Iowa last night or the other night that said that she's still doing quite well there.

So, I think it's a legitimate issue that people should look at. I just don't think that it's the threat to her long-term political viability some say it is.

TAPPER: One could argue that the reason that she's been able to avoid any harm from this is that she has avoided any questions about it. She has really kept the press at arm's length during all of her various trips. She hasn't given any significant interviews. Is this a smart strategy or do you think it ultimately will backfire?

PFEIFFER: Well, I think, over the course of time -- it's important to remember she hasn't even done the official announcement of her campaign yet. Over the course of time, she's going to have to engage with the press. They will be critical to her success. I think that, whenever you're in a situation like this, as I was when I was working for President Obama, you want to make sure that you run your campaign strategy, and not -- and don't do it on the schedule the press sets. But what you can't do is go so long without talking to the press that it bubbles over into a world where every single little interaction you have becomes carried on live television.

And so you have got to find that right balance. As the campaign goes on, I think they are going to be able to do that.

TAPPER: But I guess some of the questions, she doesn't want to answer questions, for instance, about the Clinton Foundation, about whether there not were -- or not whether -- I mean, about why there were violations of the ethics agreement that the Clinton Foundation entered into with the White House -- you remember this -- when she agreed to become secretary of state.

There was a very intense negotiation. And a lot of those arrangements were not adhered to by the Clinton Foundation. That's a fair question to ask about. Also, she hasn't really come out and stated her position on this Pacific trade partnership that a lot of liberals, like Bernie Sanders and Elizabeth Warren, oppose.

There are substantive questions that she's avoiding that I don't understand why just putting them off until she has to do them makes it any better.

PFEIFFER: Well, look, those are no -- there's no question those are legitimate questions. And she is going to have to address all of those and a lot more over the course of this campaign. And she's probably going to have to do it sooner rather than later.

She is going to have an announcement in a short while here. And after that, I suspect that her engagement with the press is going to have to increase. But if she doesn't answer those questions, that will hurt her in the long run. I'm not sure it has yet. But in the long run, you have to -- you're going to have take those on, or it's going to -- it will add up over time.

TAPPER: I want to turn to the struggle that the White House is facing right now in terms of its national security message, and the fact that the president clearly wanted those powers in the Patriot Act renewed. They were not ultimately renewed.

I understand that the Republicans control both the House and the Senate, but some look at this and see a larger problem. Ron Fournier, for example, writing in "The National Journal" today, said that: "The greatest threat to democracy is not the rise of ISIS, Iran and lone wolf attacks. The greatest threat is this, Americans no longer trusting the people and institutions protecting them."

Now, Fournier goes on to argue that one of the reasons for that is James Clapper not being honest about the collection of data, and President Obama not holding him accountable.

Do you think that is a fair analysis? PFEIFFER: Look, I think that the -- I don't know that I would say

that it's the greatest threat to democracy.

But decreasing trust in public institutions, which is something that has been going on for decades in this country, is a real problem in our democracy. And it's incumbent upon every president, this one included, to try to rebuild that. And they're going to have to work hard on that, I think, no doubt.

TAPPER: But don't you think that not holding James Clapper accountable, not even expressing publicly dismay with the fact that I think it's tough to argue he did anything but lie before Congress and the American people about the metadata program -- you can argue that he did it for a national security reason, but, clearly, he was lying -- that -- that not even expressing dismay hurt, ultimately, the president's ability to keep the powers he wanted to keep?

PFEIFFER: I don't think it -- I don't think that's true in this case.

I think we had a very specific problem in this country about trying to get the Patriot Act renewed. And it was a problem between the junior senator in Kentucky and the Senate majority leader from Kentucky. And that is not a -- that doesn't go to the president. I don't think Rand Paul is making his campaign decisions because of what the president did.

TAPPER: All right.

[16:35:00]

Dan Pfeiffer, thank you so much.

PFEIFFER: Thank you.

TAPPER: Congratulations again. We're glad to have you on board here.

In our national lead today, American security put to the test. Undercover agents hid fake guns and explosives and tried to get these mock weapons onto airplanes. And guess what? It worked. Does the security lapse put your safety at risk? That's next.

(COMMERCIAL BREAK)

TAPPER: Welcome back to THE LEAD. I'm Jake Tapper.

Making some big headlines in our national lead today, a major security breach exposing potential threats to the safety of millions of air travelers every single day. Internal government tests designed to challenge the TSA revealed that undercover agents successfully smuggled fake explosives and weapons through checkpoints nearly 100 percent of the time.

CNN aviation correspondent Rene Marsh has the details.

(BEGIN VIDEOTAPE) RENE MARSH, CNN AVIATION CORRESPONDENT (voice-over): TSA officers failed 95 percent of the time during undercover operations designed to test their ability to detect explosives and weapons at airport security checkpoints.

[16:40:10]

CHAD WOLF, FORMER TSA OFFICIAL: These are anomalies that TSA screeners and/or equipment should locate and at least flag for an additional screening.

MARSH: Teams with the Department of Homeland Security Inspector General's Office posed as passengers and attempted to pass through airport checkpoints with mock explosives and weapons. A government official with knowledge of the results say TSA failed 67 out of 70 tests.

WOLF: To miss 67 out of 70 different instances is extremely alarming, and I would say even dangerous.

MAN: I am putting a detonator into the plastic explosive.

MARSH: CNN was there in 2008 for a similar covert operation. That time, it was TSA testing its own officers.

UNIDENTIFIED MALE: Can't see anything?

UNIDENTIFIED MALE: No, I can't see anything.

UNIDENTIFIED MALE: OK.

MARSH: At the checkpoint, the testers wanded and patted down where the fake explosive device was concealed, but the screener missed it. It's not until the tester lifts his shirt up.

UNIDENTIFIED MALE: Oh, I see it now.

MARSH: The Department of Homeland Security says it -- quote -- "immediately directed TSA to implement a series of actions, several of which are now in place."

WOLF: Is it the technology that is failing or is it the screeners themselves not following proper protocol? If TSA's screening equipment is failing and not doing the job, that's a larger systemic issue that TSA needs to address.

(END VIDEOTAPE)

TAPPER: Our thanks to Rene Marsh for that report.

Now, we want to hear from you. What changes do you want to see at the TSA? Tweet us @THELEADCNN or sound off on our Facebook page.

Coming up, how did the killers or killers get into a mansion and murder a family and their housekeeper in Washington, D.C.? An employee of the family speaks to CNN about the security system at the house. Plus, a critical clue that police found in the garage, that's coming up next.

Also, one man searching for a woman who accidentally gave away one of the first Apple computers ever made, and it's worth more than some houses -- that's also coming up.

(COMMERCIAL BREAK)

TAPPER: Welcome back to THE LEAD. I'm Jake Tapper. New information revealed in today's National Lead about the four mysterious murders in a D.C. mansion, now on the day of the funerals of the victims, new information emerging about the wealthy family and their housekeeper.

We may now know why there were no signs of forced entry into their home. The revelation comes almost two weeks after the brutal murder of Savvas Savopoulos, his wife, their 10-year-old son and their housekeeper.

So far police only charged one person, Daron Wint in the murders, but more arrests may soon be on the way. CNN's Pamela Brown has been following the story from the very beginning. Pamela, what have you learned?

PAMELA BROWN, CNN JUSTICE CORRESPONDENT: Well, Jake, today as the Savopoulos family was laid to rest, we are learning more from one of the longtime housekeepers that worked for the family for 20 years about how the suspects may have gained entry into the Savopoulos home before the murders and hearing from an attorney who just met with the only suspect in this case, Daron Wint.

(BEGIN VIDEOTAPE)

BROWN (voice-over): Following behind three caskets draped in white flowers, the daughters of Savvas and Amy Savopoulos said good-bye to their parents and little brother, Philip, in Washington, D.C. today.

They were found brutally murdered along with the family's housekeeper last month. So far police have arrested one suspect, 34-year-old Daron Wint, but believe he didn't act alone. An attorney for Wint met with him in jail over the weekend and tells CNN Wint says he's innocent.

ROBIN FICKER, WINT ATTORNEY: He suggested they look at people who have recently worked for the victim, who were insiders and who knew about the large amounts of money that he was dispensing.

BROWN: Wint worked for the Savopoulos' company, American Ironworks, more than ten years ago. D.C. police say they found his DNA on pizza crust inside the family's home. Legal analysts say even if Wint didn't kill anyone, he could still be held responsible?

DANNY CEVALLOS, CNN LEGAL ANALYST: If you are involved in any way you can expect the prosecution will charge you as a defendant accomplice and in most jurisdictions, helping someone commit a murder is punishable as if you had committed the murder yourself.

BROWN: Today a longtime housekeeper of the Savopoulos family tells CNN she's not surprised there were no signs of forced entry into the home. She says the house was normally unlocked. The security system was rarely turned on, and the family often kept the garage door open.

As three members of the Savopoulos family were laid to rest, questions remain as to why they lost their lives.

(END VIDEOTAPE)

BROWN: And we know testing of other DNA found in the family's home including fingerprints on a water bottle are still ongoing apparently. So far no one else has been named a suspect including the assistant of Savvas Savopoulos who allegedly lied about dropping off the $40,000 in ransom money according to court documents -- Jake.

TAPPER: Pamela, the longtime housekeeper to whom you referred also talked about the father's assistant. What did she have to say?

BROWN: She said she met him back in March. She recently started working for the family and she said that he worked at the family's home and also drove Mr. Savopoulos.

She said the last time she had seen or heard from him was the day before the murders. She said that he was at the martial art center that Savvas Savopoulos was trying to open.

That he left at around 3:30 p.m. that day and she said she has spoken to a lot of people since the murders who knew the family and no one had seen or heard from him.

We have been reaching out at well and haven't heard back. His friends haven't heard from him. It's very much a mystery. We know police are still looking at him and still investigating him, and looking for more clues as to what may have happened here.

Also, we're learning from the Wint family attorney who was in my piece that they have never heard of the assistant before -- Jake.

[16:50:05] TAPPER: Pamela brown, thanks so much.

Continuing our National Lead, it's a new era in treating cancer so says the author of a study hailing a new cancer treatment, a combination of two drugs helping unlock the immune systems potential to fight melanoma, a deadly skin cancer that can spread to places such as the lungs or brains.

Immunotherapy as it's called, stopped the disease from advancing in nearly 60 percent of the cases. This immune system based treatment is especially promising for those who suffer from cancers that are difficult to treat because they spread throughout the body. Doctors did caution that this particular treatment does come with increased side effects.

Our Money Lead now, a Silicon Valley Recycling Center is searching for a woman to whom they want to give $100,000. A California woman cleaned up her garage and donated some electronic waste to the facility and unknowingly dumped an antique Apple 1 computer, only 200 of its kind were made in 1976 selling for $666.66 at that time.

The recycling center sold the computer for $200,000 to a private collector but have a policy of splitting their windfalls, 50/50 with the donor. The mystery woman did not leave behind a name, or phone number or even take a receipt.

Wolf Blitzer now joining us with a preview of "THE SITUATION ROOM." Wolf will be talking about the NSA halting its bulk phone data collection and whether or not we're less safe today. Who do you have coming up on the show?

WOLF BLITZER, CNN HOST, "THE SITUATION ROOM": We have the chairman of the House Armed Services Committee Mack Thornberry who is going to be joining us. He's got some strong views on what's going on as a lot of members of the House and Senate have very strong views.

Also Representative Adam Kinsinger, he is an Iraq war veteran, we'll talk to him about this. And also this very disturbing report now that when the Iraqi military abandoned Mosul, the second largest city in Iraq about a year ago, they left behind about 2,300 -- 2,300 -- U.S. Humvees.

These armored personnel carriers and that they are using -- ISIS is now using these Humvees in various ways including launching suicide bomb attacks moving into various areas to kill Iraqi soldiers with these Humvees. So we've got a lot more coming up on that and all the days important news right at the top of the hour.

TAPPER: All right, it sounds great. Thanks, Wolf. Coming up, his family and friends are remembering him as the finest man they have ever known. Joe Biden's son dies at age 46. Coming up next, memories of Beau Biden.

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[16:56:43]

TAPPER: Welcome back to THE LEAD. Now for a story I never warranted to report. Vice President Joe Biden is a man who back in 1973 took his Senate oath of office at the bedside of his children after a crash killing his wife and daughter.

Today, the Biden family is once again mourning and trying to come to terms with the tragedy, the loss of the son of the vice president, Beau Biden. Joseph Beau Biden III, an Iraq war veteran, served at the attorney general of Delaware died on Saturday.

He was battling brain cancer according to the vice president's office. Beau Biden was just 46 years old. The vice president and his entire family were at his side when he died.

Beau Biden shocked many political insiders when he turned down a chance to run for the Senate seat his father vacated when he first became vice president back in 2008.

Beau instead devoted himself to his country in another way as a major in an Army National Guard unit that deployed to Iraq in 2008. The White House released a statement saying Beau Biden, the father of two, was quite simply the finest man any of us have ever known.

I personally knew Beau. I've known him since the early '90s. He was a fine man. He was a man of honor and integrity. We would like to send our prayers and condolences to the Biden family, a family that has endured way too much heartache already.

Now let's turn to another story, a birthday of sorts, 35 years ago the Cable News Network, CNN launched a visionary idea for a channel bringing you the world's news at all hours not just once in the morning and once a night.

Tonight, look back with us in a special report "Breaking News: 35 Years Of CNN." Here's just a peek at one of the stunning moments that broke on CNN's air and put the network on the map.

(BEGIN VIDEOTAPE)

UNIDENTIFIED MALE: We are going to Bernard Shaw in Baghdad.

BERNARD SHAW: This is -- out of my mouth came the words. Something is happening outside. You are dam right, something is happening. War is breaking out all around you.

The skies over Baghdad have been illuminated. We are seeing bright flashes going off all over the sky.

The walls were shaking. The windows were vibrating. The concussions were blowing us against the wall.

UNIDENTIFIED MALE: So we have now been on the air 20 minutes.

PETER ARNETT: Now the sirens are sounding for the first time. The Iraqis have informed us --

The line goes dead.

[07:45:10] UNIDENTIFIED MALE: They cut the line.

ARNETT: Everybody is stunned and it's totally silent and you can feel the tension in that room.

SHAW: And John Holliman said it's the battery. Battery is dead.

ARNETT: Of course, our biggest fright was the bomb had hit the hotel where they were. There was a hush in the control room.

SHAW: We find Holliman does work around.

JOHN HOLLIMAN: Hello, Atlanta.

SHAW: We come back on the air.

HOLLIMAN: Atlanta, this is Holliman, I don't know if you are able to hear me or not, but I'm going to get in to talk to you as long as I can.

ARNETT: There is a collective sigh. You see shoulders drop down as the tension leaves people's body.

BLITZER: The whole world was watching CNN. We were the only ones that had reporters in Baghdad.

(END VIDEOTAPE)

TAPPER: Be sure to watch CNN Special Report, "Breaking News 35 Years Of CNN" that's tonight at 9 p.m. and then after that make sure to tune in to Conan O'Brien tonight. I'll be his guest.